Abstract: A thermally stabilized optical filter device includes a multilayer optical bandpass filter on a transparent substrate, with the transparent substrate being composed of a material having a first coefficient of thermal expansion. An encasement surrounds the transparent substrate such that the bandpass filter is exposed for transmission of predetermined optical wavelengths there through. The encasement is composed of a material having a second coefficient of thermal expansion that is different than the first coefficient of thermal expansion. The encasement provides thermal stability to the optical properties of the bandpass filter by compensating for changes in the filter that occur with temperature variations. In another embodiment, a collet assembly provides means for selectively compressing a filter chip to tune the filter response.

Abstract: A multiple channel optical multiplexing/demultiplexing system utilizes a beam splitter to divide a single multi-wavelength beam of optical energy into two multi-wavelength beams, or to combine a plurality of multi-wavelength beams into a single output beam. In the demultiplexing configuration, a pair of demultiplexers are configured to receive and separate the two multi-wavelength beams into a plurality of wavelength channels. The two multi-wavelength beams are thus demultiplexed in parallel, allowing greater efficiency by avoiding excess beam attenuation. The individual demultiplexers can be incorporated into a single unitary device or can be optically interconnected as separate parts. Alternatively, the demultiplexing system can use multiple beam splitters to divide a single input multi-wavelength beam into a plurality of multi-wavelength beams for parallel demultiplexing in a plurality of demultiplexers.

Abstract: A color measuring sensor assembly includes an optical filter such as a linear variable filter, an optical detector array positioned directly opposite from the optical filter a predetermined distance, and a coherent fiber faceplate having a plurality of optical fibers interposed between the optical filter and the detector array. A light beam propagating through the fiber faceplate from the optical filter to the detector array projects an upright, noninverted image of the optical filter onto a photosensitive surface of the detector array. Each optical fiber in the fiber faceplate is of limited aperture to control the tendency of light to diverge and to increase the resolution capabilities of the sensor assembly. The color measuring sensor assembly can be incorporated with other components into a spectrometer device such as a portable calorimeter having a compact and rugged construction.

Abstract: An attenuation filter contains absorbing thin film layers, which comprise gray metals or metal compounds. The attenuation filter offers significant advantages when used in optical communication systems subjected to a relatively high flux of incident light. It was surprisingly discovered that particular thin film materials provide significant protection to the attenuating thin film layer thereby improving the temporal stability and power handling capacity over prior art devices.

Abstract: An index-matching coating is applied directly to a low-emissivity (“lowE”) thin-film coating. Nodules growing from a site in the lowE coating are removed to avoid propagation of defects through the layers of the index-matching coating. A tempering step in an oxygen-containing atmosphere produces compressive stress in the lowE coating and hardens the coating. The compressive stress facilitates removal of the nodules and the hardening allows mechanical cleaning of the lowE coating prior to the index-matching coating, further removing nodules. Magnesium-fluoride is used as the final layer of the index-matching coating in one embodiment to improve abrasion resistance. The resulting glass panel may be used as a display panel in a plasma display or an organic light-emitting diode display, for example.

Abstract: Multiple channel multiplexing/demultiplexing devices include an optically transparent optical block seated atop an optically transparent beam-directing member. The optical block includes a plurality of wavelength selective elements, a plurality of reflectors, and at least one imaging optical element. The beam-directing member includes a beam folding mirror and focusing lenses. When the devices are used as demultiplexers, a multi-channel beam is directed into the optical block and relayed in a zigzag pattern onto the wavelength selective elements, which separate selected wavelengths from the beam. The separated wavelengths propagate through the beam-directing member and are focused onto optical receptors.

Abstract: A multi-cavity optical device allowing selective control of a bandpass characteristic thereof . Fabry-Perot structures are coherently coupled together to form a narrow bandpass structure. At least one of the spacer regions in the device includes an active material that changes the optical thickness of the spacer to de-tune the device. In one embodiment, the active material is transparent and lies along the optical path through the device. In another embodiment, an active material that lies outside of the optical path tunes an air gap. Altering the first or last spacer in a multi-cavity structure provides variation in the transmission loss while generally retaining a flattop filter response with low passband ripple. Altering interior spacer regions provides high sensitivity to variations in the optical thickness of the spacer.

Abstract: An optical fiber coupling assembly includes an optical fiber receiver, an optical spacer, and an optical filter such as a linear variable filter. The optical spacer can comprise either a monolithic block of optically transparent material, or an optical cavity within reflective walls. The fiber receiver can comprise either a machined attachment on an opaque lightweight block or can be a surface on the optical spacer configured to receive and adhesively bond an optical fiber. The optical spacer recirculates light that is incident on an optical filter segment that is not within the segment's designated wavelength range, thereby permitting multiple passes of the light within the assembly. A color measuring sensor device using the fiber coupling assembly can be incorporated with other components into a spectrometer device such as a portable calorimeter having a compact and rugged construction suitable for use in the field.

Abstract: The absorption of a spacer material in a Fabry-Perot type structure is changed to achieve an optical switching function. In one embodiment, the spacer material is a semiconductor material and an electronic control signal changes the Fabry-Perot between a transmissive state and a reflective state. In the reflective state, the device operates as a switch can be modeled as a mirror on a substrate of quasi-infinite thickness. In a further embodiment, a wavelength-selective optical component is placed between the input of the switch and the Fabry-Perot structure to improve the spectral response of the switch.

Abstract: This invention relates to attenuation filters having absorbing thin film layers, which comprises gray metals or metal compounds. The attenuation filters offer significant advantages when used in optical communication systems wherein they are subjected to a relatively high flux of incident light. It was surprisingly discovered that particular thin film materials provide significant protection to the attenuating thin films layer thereby improving the temporal stability and power handling capacity over prior art devices.

Abstract: An optical switch using a refractive optical element (52) to direct a light beam in selected directions upon operation of the switch. In a preferred embodiment, the refractive optical element is an optical wedge having a first portion (67) that transmits a light beam in a selected direction, and a second portion (50) that transmits the light beam in another direction, when the first or second portions of the optical wedge are switched into the path of the light beam. The refractive optical element is less sensitive to misalignment than a reflective element, for example. In a further embodiment, the optical wedge is combined with wavelength-selective filters (118, 128) and other components to provide a channel DROP and/or ADD function with high isolation.

Abstract: A multiple channel optical multiplexing/demultiplexing system utilizes a beam splitter to divide a single multi-wavelength beam of optical energy into two multi-wavelength beams, or to combine a plurality of multi-wavelength beams into a single output beam. In the demultiplexing configuration, a pair of demultiplexers are configured to receive and separate the two multi-wavelength beams into a plurality of wavelength channels. The two multi-wavelength beams are thus demultiplexed in parallel, allowing greater efficiency by avoiding excess beam attenuation. The individual demultiplexers can be incorporated into a single unitary device or can be optically interconnected as separate parts. Alternatively, the demultiplexing system can use multiple beam splitters to divide a single input multi-wavelength beam into a plurality of multi-wavelength beams for parallel demultiplexing in a plurality of demultiplexers.

Abstract: Multiple channel multiplexing/demultiplexing devices include an optically transparent optical block seated atop an optically transparent beam-directing member. The optical block includes a plurality of wavelength selective elements, a plurality of reflectors, and at least one imaging optical element. The beam-directing member includes a beam folding mirror and focusing lenses. When the devices are used as demultiplexers, a multi-channel beam is directed into the optical block and relayed in a zigzag pattern onto the wavelength selective elements, which separate selected wavelengths from the beam. The separated wavelengths propagate through the beam-directing member and are focused onto optical receptors.

Abstract: A wavelength-selective filter, such as a narrow bandpass filter, is used to filter both the input and output of an optical amplifier. The selected channel is amplified and can be re-combined with the other original channels or provided to another output, depending on amplifier configuration. In a particular embodiment, a two-stage amplifier with center stage access uses a single gain-flattening filter to compensate for gain tilt of both amplifier stages.

Abstract: An optical cross-connect is fabricated on a substrate using individual MEMs dice with mirrors that rotate into and out of an optical beam path. Each die can be aligned to a single (input-output) pair of collimators in a fiber-optic switching system. An individually accessible magnetic drive on each die provides low power consumption when re-configuring the array in addition to fast switching speeds. The state of each die can be electronically sensed to verify proper array configuration and operation of each die.

Abstract: An image projection display system is provided which utilizes an off-axis illumination configuration. A beam splitter is configured to direct a first light beam along a first optical path toward reflective imaging devices adapted to direct a second light beam along a second optical path to produce an image to be projected. Polarizing devices are interposed between the beam splitter and each imaging device, with the polarizing devices configured to allow passage of a first polarized component of the light beam while blocking passage of a second polarized component of the light beam. The display system provides a high contrast ratio and degree of brightness which significantly improves the final image quality projected to a display screen.

Abstract: An optical assembly including a wavelength selective filter (114) in combination with a collimator (112). An input port is configured to provide an optical signal containing a plurality of optical channels to the collimator and then to the wavelength selective filter. The hybrid selective optical router allows a channel or segment of adjacent channels (118) to be dropped from the optical signal with minimal signal degradation to the dropped or expressed channels. In a particular embodiment, a pair of wavelength selective routers (300, 326) are combined with a switched optical directing element (308) and other components to provide an ADD/DROP switch. In a further embodiment, an ADD/DROP switch is provided with a single movable mirror, and no fixed mirrors.

Abstract: A switching signal having multiple sequential pulses is applied to a MEMS switch. A first pulse moves the switch from a first switch position toward a second switch position. After a selected dwell period, a second pulse is applied to dampen ringing or overshoot of the movable portions of the switch. In a further embodiment, non-symmetrical switching signals are used to cycle the switch from the first state to the second state, and back to the first.

Abstract: An optical amplifier assembly integrating wavelength selective input and output filters. Integration of wavelength selective filters with a doped fiber optical amplifier stage provides a modular amplifier for use in wavelength division multiplexed optical communication systems. In one embodiment, a center tap provides access to the selected light signal after a first amplifier stage, allowing signal modification before returning the light signal to a second amplifier stage of the integrated amplifier. In a further embodiment, a pump interconnect is provided between the first and second amplifier stages to allow operation of both amplifier stages from a single pump light source.

Abstract: Methods and apparatus for enhancing the performance of a reflective liquid crystal display system. The high-contrast color splitting prism system utilizes a “double-passed” prism assembly. Polarized light enters the prism assembly, is color-split and emitted as separate colors to spatial light modulators which reflect each color in accordance with a desired image. The reflective light is passed, once again, through the prism assembly where the separate colors converge and propagate to a projection lens for display of the image on a screen. A waveplate retarder is positioned between the liquid crystal display and the polarizing element. The waveplate retarder is tilted with respect to the optical axis to eliminate the deleterious effects of the Fresnel reflections at the interfaces of the waveplate retarder.